1b.Approach (from AD-416)
Postharvest insects cause significant economic loss to the agricultural sector, both through direct damage by feeding or product contamination, and by the cost of control programs. The export trade of certain horticultural products may be affected as well, with importing countries requiring quarantine treatments to prevent the introduction of exotic pests. Of particular concern to agriculture in the Western U.S. are field pests such as the olive fruit fly (Bactrocera oleae), navel orangeworm (Amyelois transitella), and codling moth (Cydia pomonella), and storage pests such as the Indianmeal moth (Plodia interpunctella). Processors rely largely on chemical fumigants such as methyl bromide for insect disinfestation, but regulatory, environmental and safety concerns mandate the development of non-chemical alternatives. In addition, with the elimination of methyl bromide as a fumigant because of its ozone depletion, the development of alternatives is an immediate concern. This project addresses this problem with a broad collaborative approach, examining both preharvest, biologically based control strategies as well as physical postharvest disinfestation treatments. Areas of investigation will include the development of biological and cultural control practices for olive fruit fly, improved field control of navel orangeworm with mating disruption and entomopathogenic nematodes, improved sex pheromone of navel orangeworm, new microbial controls for stored product beetles, commercial-scale forced hot air control atmosphere treatment for stone fruits, volatile markers to identify suitable hot forced air treatments for citrus, and radio frequency heating, low temperature storage, vacuum treatments, and parasitoid releases for control of postharvest dried fruit and nut insects. New, non-chemical methods for control of these economically important pests will be the outcome of this research. Formerly 5302-43000-031-00D (03/08).

3.Progress Report
A regional biological control program to control olive fruit fly using a parasitoid imported from Guatemala was conducted from August 2008 through February 2009. The dispersal capacity of olive fruit fly adults on the ground and methods to contain adult emergence from the soil were studied in laboratory and greenhouse tests. Procedures to rear olive fruit fly on formulated diet were simplified to produce large numbers of insects with minimal labor. Field and laboratory data were collected to elucidate effects of dispersal and delayed mating on mating disruption treatments for navel orangeworm. Data from mark-capture experiments and analysis of damage in almond orchards bordering sources of high navel orangeworm abundance were combined with daily fecundity data for newly-emerged females. Together these data indicate that, while the navel orangeworm is capable of inter-orchard dispersal, most oviposition and damage occurs within 100 yards of the site of pupation. Volatile collection devices and procedures for collection of pheromone blends were refined and are being used to elucidate release ratios of navel orangeworm sex pheromone components from synthetic sources. Bioassay methods to assess attractiveness of pheromone blends were improved for rapid discrimination among blends by test insects. Field trapping of navel orangeworm show that trap saturation begins at about 50 males per trap; further studies will lead to equations that relate trap catch to actual trap visits and population size. Insect-pathogenic nematodes were applied to an 80 acre pistachio orchard (500 million infective juveniles per acre) through the sprinkler system and evaluated using infested sentinel pistachios. Although inadequate control was obtained due to unusually low nighttime temperatures occurring during the first three days after application, the results help establish the field conditions necessary for success. Heat treatments of varying durations were imposed upon navel oranges to determine the heat threshold beyond which flavor is negatively affected. A level of cumulative heat exposure was defined which caused a loss of flavor quality and an increase in the occurrence of off flavors. Measurements within individual single-layer boxes were conducted to map airflow patterns and heat transfer within and among palletized boxes of stone fruit in an attempt to better optimize the forced-air heating of stone fruit in boxes. The parasitoid Habrobracon hebetor was released into almonds infested with overwintering Indianmeal moth to determine the effect of the parasitoid on insect fragment levels. Dielectric properties of cowpea weevils dissected from black-eyed peas were determined. Methods to determine the thermal death kinetics of the cowpea weevil were developed, and late larvae and pupae were determined to be the most heat tolerant stages. Data on the relative heat tolerance of different stages of the peach twig borer and raisin moth were also collected. The above research seeks to reduce postharvest use of methyl bromide for either perishable or durable commodities, and to protect postharvest commodities from pests through ecologically sound means.

4.Accomplishments
1.
Biological and Cultural Control of Olive Fruit Fly. Olive fruit fly has become a major pest of olives in California, the nation's major producer of canned olives. ARS scientists at the San Joaquin Agricultural Sciences Center, Parlier, CA implemented a biological control program to reduce the pest in different regions of the state by releasing large numbers of an imported parasitoid in infested olive groves. Methods to attract, contain, and limit the distribution of olive fruit fly by trapping techniques in laboratory and greenhouse tests to determine feasibility for use in olive orchards were evaluated. Adoption of biological control of the olive fruit fly will protect California's olive and oil industry valued at 75 million dollars annually.

2.
Effect of Temperature and Available Water on Navel Orangeworm (NOW) Longevity and Reproduction. As mating disruption and other tactics are used with area-wide approaches for control of navel orangeworm, understanding of life history properties has become important. An ARS scientist at the San Joaquin Valley Agricultural Sciences Center, Parlier, CA, in collaboration with Paramount Farming Company, found that navel orangeworm longevity in the first and second flights is proportional to degree-day accumulation, and that the reproductive capacity of navel orangeworm varies with the availability of water to adults. This work will improve protection of almonds, pistachios, figs, and walnuts; collectively are worth more than $3 billion.

3.
Non-saturating Traps for Male Navel Orangeworm. Populations of navel orangeworm, a serious pest of tree nuts, are currently monitored using traps baited with virgin female moths, but traps fill quickly. Studies with commercial traps showed that trap capture efficacy decreases after about 50 males are trapped. ARS entomologists at the San Joaquin Valley Agricultural Sciences Center, Parlier, CA developed a large sticky trap with 30x more trapping area than commercial traps that greatly increases the trap saturation time. This work will result in models relating trap catch to actual moth numbers and will lead to better management of this pest and a reduction of pesticide use.

4.
Entomopathogenic Nematodes Used to Control Overwintering Navel Orangeworm. Navel orangeworm (NOW), the primary pest of pistachio, overwinters in fallen nuts and currently there is no economic treatment to control NOW population. ARS scientists at the San Joaquin Valley Agricultural Science Center, Parlier CA, conducted research to determine how best to use insect pathogenic nematodes against this insect during the overwintering period. Numerous trials demonstrated that nematodes were effective when applied through the irrigation system and when nighttime temperatures were above freezing. This treatment can be used by both conventional and organic growers to improve control of navel orangeworm.

5.
Determination of the Heat Exposure Threshold to Maintain Flavor Quality of Heat-treated Navel Oranges. Heat treatments are an effective and safe means of controlling insect pests but can harm flavor in navel oranges. Researchers at the ARS San Joaquin Valley Agricultural Sciences Center, Parlier, CA determined that 150 minutes at 45 °C was the upper limit of heat exposure that did not adversely affect fruit flavor. Knowledge of this heat treatment threshold for flavor quality will help researchers determine whether heat application is a viable treatment for controlling insect pests in navel oranges.

6.
Determination of the Most Heat Tolerant Stage of the Cowpea Weevil. Heat treatments provide a non-chemical means of controlling Cowpea Weevil. However Cowpea Weevils cause damage to leguminous crops, and pose a serious concern to export markets. Therefore, affective heat treatments require that the most heat tolerant pest stage be identified. ARS scientists at the San Joaquin Valley Agricultural Sciences Center, Parlier, CA used a heat block developed by collaborations at Washington State University to determine that the late larval and pupal stages are the most heat tolerant for the Cowpea Weevil. This information will be used to develop fast, non-chemical heat treatments using radio frequency energy, reducing the need for environmentally-damaging fumigants.